It is standard practice when completing, or performing remedial work down the tubing, on wells to use of an array of valves, which are sometimes referred to as "christmas trees". Christmas tree arrays of valves on wells are generally very expensive, complicated and cumbersome. Unfortunately such arrays can experience leakage problems in each valve, or at each coupling thereto, resulting in costly and time consuming repairs, and temporary loss of production. Corrosion of the arrays can also necessitate replacement of one or more of the valves. Furthermore, care must be exercised when moving heavy equipment in an oil field not to accidentally bump into and damage the christmas tree arrays. Earthquakes can also cause damage to such arrays because of their weight and cantilevered configurations.
These christmas tree array problems were greatly alleviated by use of diversionary spool assembly ("DSA"), disclosed in my U.S. Pat. No. 4,804,045. The DSA alleviated the need for the christmas tree array of valves, however, in addition to the DSA there is a requirement for one or more additional and separable pieces to serve as a tubing hanger. Assembly of the separable tubing hanger pieces to the DSA, of course, requires time, and its presence in the string provides one or more additional separable joints which can develop leaks or other problems. Accordingly, there is an ongoing need for additional simplification to further reduce the number of component parts in wellhead operations when completing, or controlling, or performing remedial work. Separable tubing hangers are also disclosed in U.S. Pat. No. 3,299,958 and my U.S. Pat. Nos. 4,491,176 and 4,708,201 and 5,148,865. A christmas tree valve supporting assembly is also shown in U.S. Pat. No. 4,491,176.
Except for rod pump completions, when wells are completed, seal plugs are installed the vertical bore leading to the tubing string. Seal plugs are disclosed in my U.S. Pat. Nos. 4,804,045 and 5,148,645, and an expandable seal plug in my U.S. Pat. No. 5,000,719. These seal plugs, however, can not be used in rod pump completions. Accordingly, there is also a need in rod pump completions for an in-place emergency rod seal which can be used in the vertical passageway between the pump rod and the vertical passageway containing the rod, which can serve as a backup emergency seal in case of packing gland leakage around the pump rod.